After the scans revealed the nature of the injury, Ferguson would have been less sanguine at the realisation that his club will be the only loser. Happily for the England manager, the prognosis on Rooney's wrenched ankle suggests he will be back to full fitness well inside a month, while he can enjoy a little overdue rest and recuperation from a demanding season, and dream about the summer.
The timing is not propitious for a United side that Ferguson had suggested was hitting peak form. Rooney's recuperation coincides with a crucial run of four fixtures. Today's lunchtime showdown with Chelsea is followed by an awkward Champions League second leg against Bayern Munich and demanding away trips to resentful neighbours Blackburn and Manchester City. Ferguson hopes Rooney will be back for the Manchester derby, but that assumes a smooth and rapid recovery.
United have the parts to keep going without Rooney. The problem is that the machine will require a complete strip-down and remodelling in his absence, especially as his replacement is Dimitar Berbatov, a player who is almost Rooney's polar opposite in style and character.
Rooney has thrived this season because he has taken on the responsibility and the reputation of Cristiano Ronaldo, and become the automatic focus of all his team-mates' ideas. Previously United had a winger whose inclination was to cut inside, drift past a couple of defenders and poke the ball into the roof of the net before frowning with self-love into the nearest camera lens. This season, United's wingers, Nani and Luis Antonio Valencia, talented but not extravagant players, have subsumed their own egos to the team imperative, which is; stick the ball on Wayne's receding temples as quickly and as often as possible. Thirty-four goals have been the result.
Rooney's form has rendered Berbatov a fringe player, and made the Bulgarian's free-scoring form and technical brilliance when he was at Tottenham a somewhat hazy memory. It's an understatement to point out that he isn't as direct and busy a presence as Rooney, less combative and hungry for the ball. Berbatov certainly isn't the type to be chasing back in his own half in the last minute of a match, so determinedly that he injured himself (as Rooney did against Bayern). Instead Berbatov is an elegant and calm finisher, a player who can make space and time in seemingly unpromising situations.
He has been marginalised through circumstance rather than intention. Ferguson was hardly likely to have paid 30million for a striker to look graceful on the bench. Berbatov was supposed to be a foil to Rooney (with the ill-fated Michael Owen as the plan B). When Rooney started to revel in playing as the lone spearhead in front of a busy midfield quintet though, Berbatov's fate was sealed.
United's inclination to put all their eggs in one basket might be about to come unstuck at Easter, unless they can reinvent themselves overnight. Champions tend to be sides who can present threats from several quarters.
United's opponents today, Chelsea, were in the fortunate position of having a spare striker, Nicolas Anelka, who seized the opportunity offered by his team-mate Didier Drogba's extended absence in January. Chelsea are also fortunate in having midfielders like Frank Lampard and Florent Malouda who score freely when Drogba is unavailable, conspicuously in last weekend's staggering 7-1 demolition of Martin ONeill's jaded Aston Villa.
United's midfield is far less prolific. While Lampard and Malouda have 17 and 11 league goals respectively, United's highest-scoring midfielder is Valencia, with a mere five. The venerable Paul Scholes has picked up four yellow cards for every goal he has contributed, a rather poignant illustration of a player now puffing gamely after the ball rather than smacking it past the keeper. The statistics tell the story of how steadily United's water-carriers have supplied Rooney rather than look for glory themselves.
Ferguson, dogged by injuries for much of the season, has shuffled his pack adroitly, although it has tended to be in defence where he has had to be most creative. Rooney, for most of the time, has been a force of nature, told to pull on a shirt and carry on where he left off in the previous game. This is a different kind of challenge. Ferguson's genius has been reiterated this season with his ability to make decent but unexceptional players like Darren Fletcher, Ji-Sung Park and Jonny Evans excel at the highest level. Berbatov, a complex and moody personality, probably doesn't need much persuasion to believe that he is a world-beater. The problem is fitting him into a pragmatic outfit already smoothly functioning as a supply-line for the more assiduous and determined Rooney.
The answer may be to play to his strengths as an intelligent deep-lying centre-forward who can hold up the ball and bring his team-mates into the action with intelligent and precise passing. Whether United can flourish over the next three weeks will depend on whether the likes of Park and Fletcher can tune into the Bulgarian's wavelength.